Date of Completion

Spring 4-28-2021

Project Advisor(s)

Alexander C. Jackson

University Scholar Major

Physiology and Neurobiology

Disciplines

Other Neuroscience and Neurobiology

Abstract

The lateral hypothalamic area (LHA) is a region of the mammalian hypothalamus that is a crucial modulator of behavioral homeostasis. The LHA is composed of heterogeneous neuronal populations that control diverse physiological functions including sleep, feeding, stress and metabolism. Yet relatively few of these populations and their interactions with other brain regions are well understood. A population unique to the LHA can be defined by expression of the neuropeptide melanin-concentrating hormone (MCH). MCH neurons are suggested to be a crucial regulator of homeostatic function, but their diversity and functional properties are largely unknown. Previous data has shown a unique projection of neurokinin B (NKB, encoded by the tachykinin Tac2 gene)-expressing neurons in regions regulating stress- and anxiety-related behaviors onto MCH neurons, a subset of which express the NKB receptor (NK3R). We analyzed these complex NKB projections to LHA MCH neurons in Tac2-cre mice using Cre-dependent anterograde and retrograde viral tracing techniques and identified the bed nucleus of the stria terminalis (BNST) and the central nucleus of the amygdala (CeA) as brain regions that are candidate sources of NKB input onto MCH neurons expressing NK3R. We confirmed that Tac2 neurons in the BNST and CeA send convergent GABAergic projections onto LHA MCH neurons as well as to each other and downstream midbrain and brainstem targets. This work lays an anatomical foundation for this tachykininergic circuit, which can lead to future work investigating functionality of the circuit to better understand behavioral implications.

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